Pipettes are used for transport and/or measurement of quantities of liquid, for example in a laboratory. Pipettes such as volumetric pipettes, Pasteur pipettes or transfer pipettes comprise a stem and a bulb. The stem is arranged with an opening to receive liquid that is stored in the stem. In some pipettes, the bulb is used to draw liquid into the stem. In some pipettes, liquid is drawn into the stem by capillary action. In some pipettes of this kind, the stem is provided with an air hole and the volume of liquid drawn into the stem can be controlled by positioning the air hole because liquid fills the stem by capillary action until it reaches the air hole. Generally, the bulb may be actuated to release liquid stored in the stem.
Care must be taken by a user of the pipette to accurately control liquid flow into and out of the pipette. Handling a pressure-actuated pipette is a demanding operation for the human brain and requires fine motor skills from the user. One difficulty involves gripping a round surface (i.e. of the bulb) while controlling the pressure applied to ensure that the bulb is not squeezed inadvertently during handling. Another difficulty in handling is due to the spatial accuracy required at the same time to direct the opening of the pipette to collect and deposit a liquid sample. For example, when depositing a liquid sample into a sample testing device, this must be done without losing grip on the pipette yet adequately exerting just the right pressure to ensure controlled dispensing of the liquid. If the sample is loaded into the device with too much pressure, there is a high risk of spilling and wasting the liquid sample. Furthermore, for small sample volumes, after depositing the sample, the user must remove the pipette without releasing the bulb; otherwise a significant volume of sample may be drawn back up into the stem.